Police said the boy and two other people were waiting for a westbound 63rd Street bus, when the gunman walked up and asked everyone if another bus was coming. He then walked behind the bus shelter, pulled a silver handgun and shot Gregory once, police said.

The boy staggered to a nearby trash can, where the gunman shot him three more times in the back, police said. Gregory was dead on the scene when ambulances arrived.

Nobody else was injured, police said.

An autopsy on Gregory, of the 5200 block of South Calumet Avenue, is scheduled for Thursday, the medical examiner’s office said.

Calumet Area detectives are investigating the shooting as possibly gang-related, police said. The victim was allegedly a known gang member, police said.